Yinsi Chen, Yuan Li, Heng Liu and Yi Liu
The purpose of this study is to identify the dynamic parameters of journal bearings in asymmetric rotor systems without additional test runs or excitations.
Abstract
Purpose
The purpose of this study is to identify the dynamic parameters of journal bearings in asymmetric rotor systems without additional test runs or excitations.
Design/methodology/approach
An asymmetric rotor-bearing test rig was set up for the identification experiment. Comparations were made between the measured response of the asymmetric rotor and the symmetric rotor. The mathematical model of the asymmetric rotor is established by the finite element method. The identification algorithm is based on the model of the rotor and the measured vibration response to identify bearing parameters. The influence of modeling error and measurement noise on the identification results are numerically analyzed. The dynamic parameters of the journal bearings under different rotational speeds are identified and compared with the theoretical values calculated by the perturbation method.
Findings
The experiment results show that the vibration characteristics of the asymmetric rotor and the symmetric rotor are different. The numerical evaluation of the identification algorithm shows that the algorithm is accurate and has good robustness to modeling error and measurement noise. The identified dynamic parameters agree reasonably well with the parameters derived from the theoretical bearing model.
Originality/value
The proposed identification method uses the unique vibration characteristics of asymmetric rotors to identify the bearing dynamic parameters. As the method does not require excitations or additional test runs, it is suitable for the field test.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2024-0096/
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Yinsi Chen, Yi Liu, Yuan Li and Heng Liu
Asymmetric rotating machinery supported by oil film bearings is relatively common in practical applications. The purpose of this study is to propose a method for estimating the…
Abstract
Purpose
Asymmetric rotating machinery supported by oil film bearings is relatively common in practical applications. The purpose of this study is to propose a method for estimating the oil film parameters of the bearings in an asymmetric rotor-bearing system.
Design/methodology/approach
The proposed method requires the finite element model and translational displacement responses at the center of mass and bearings locations to form a regression equation to estimate the unknown parameters. Due to the transverse stiffness of the asymmetric rotor is not symmetrical, the analysis and parameter estimation procedures are performed in a rotating coordinate. Numerical simulations were carried out to illustrate the vibration characteristics of the asymmetric rotor system. The proposed method is applied to the simulated responses to estimate the assumed oil film parameters. The influence of the estimated parameter deviations on the rotor dynamic characteristics is discussed.
Findings
The vibration characteristics of asymmetric rotors are different from those of symmetrical rotors. The bearing parameters estimated by the proposed method are close to the assumed values, within a maximum error of 9%. The deviations of the estimated parameters have little effect on the vibration characteristic of the rotor system.
Originality/value
The proposed method does not require changing the rotational speed or applying additional excitation force to the rotor, which is suitable for the field test.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2023-0111/
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Zhihong Gao and Susan O’Sullivan-Gavin
Given the unique cultural-political context of China, this paper aims to investigate two research questions: What has been the development trajectory of policy-making on consumer…
Abstract
Purpose
Given the unique cultural-political context of China, this paper aims to investigate two research questions: What has been the development trajectory of policy-making on consumer privacy protection in China, and what factors have shaped its development over the years?
Design/methodology/approach
This paper adopts a historical approach and examines the development of Chinese consumer privacy policy during four periods: 1980s, 1990s, 2000s and 2010-present.
Findings
Chinese policy-making on consumer privacy protection has made steady advancement in the past few decades due to factors such as technological development, elite advocacy and emulation of other markets; however, the effects of these factors are conditioned by local forces.
Originality/value
To date, most studies of consumer privacy issues have focused on Western countries, especially the European Union and the USA. A better understanding of how consumer privacy policy has developed in China provides important lessons on the promotion of consumer privacy protection in other developing countries.
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Tore Hoel and Weiqin Chen
Privacy is a culturally universal process; however, in the era of Big Data privacy is handled very differently in different parts of the world. This is a challenge when designing…
Abstract
Purpose
Privacy is a culturally universal process; however, in the era of Big Data privacy is handled very differently in different parts of the world. This is a challenge when designing tools and approaches for the use of Educational Big Data (EBD) and learning analytics (LA) in a global market. The purpose of this paper is to explore the concept of information privacy in a cross-cultural setting to define a common point of reference for privacy engineering.
Design/methodology/approach
The paper follows a conceptual exploration approach. Conceptual work on privacy in EBD and LA in China and the west is contrasted with the general discussion of privacy in a large corpus of literature and recent research. As much of the discourse on privacy has an American or European bias, intimate knowledge of Chinese education is used to test the concept of privacy and to drive the exploration of how information privacy is perceived in different cultural and educational settings.
Findings
The findings indicate that there are problems using privacy concepts found in European and North-American theories to inform privacy engineering for a cross-cultural market in the era of Big Data. Theories based on individualism and ideas of control of private information do not capture current global digital practice. The paper discusses how a contextual and culture-aware understanding of privacy could be developed to inform privacy engineering without letting go of universally shared values. The paper concludes with questions that need further research to fully understand information privacy in education.
Originality/value
As far as the authors know, this paper is the first attempt to discuss – from a comparative and cross-cultural perspective – information privacy in an educational context in the era of Big Data. The paper presents initial explorations of a problem that needs urgent attention if good intentions of privacy supportive educational technologies are to be turned into more than political slogans.